Rust-inhibiting compositions



Patented Nov. 13, 1951 RUST-INHIBITING COMPOSITIONS John William Bishop, Plainfleld. N. J., asslgnor to Tide Water Associated Oil Company, Bayonne, N. J., a corporation of Delaware No Drawing. Application October 22, 1948, Serial No. 56,061

Claims. (01.106-14) The present invention relates to rust-inhibiting compositions and to the use thereof for application to metal surfaces to inhibit rusting thereof. More particularly, the invention relates to compositions particularly adaptable for prevention of rusting of ferrous metals upon exposure thereof to humid or other atmospheres conducive to metal corrosion. Hence, in practical aspect, the rust-inhibitin compositions embodied herein are adaptable for protection of metal surfaces of machine parts, en ines, drums and the like, against rusting during transportation or storage and, in certain instances, are adaptable for use as lubricating compositions with resulting protection of metal parts with which the rust-inhibiting composition is brought into contact.

' In my copending application, Serial No. 775,755, filed September 23, 1947, entitled Rust- Inhibiting Compositions, compositions are disclosed that comprise a suitable non-corrosive vehicle having dissolved therein a rust-inhibiting salt formed by an acid ester of a phosphorus acid with an alkvlolamine having an alkylol group esterified with a suitable organic acid. The salts per se are, as far as I am aware. novel compounds and, hence, have been disclosed in my copending application, Serial No. 38,743, filed July 14, 1948, entitled Esterified Alkylolamine Salts of Acid Esters of Phosphorous Acids." The present invention relates to compositions similar to those disclosed in the aforesaid application, Serial No. 775,755, in that use is made of the acid phosphate-esterified alkylolamine salts. However, in the compositions of the present invention, a suitable metal sulfonate is used in dependent combination with the aforesaid salts. As is apparent from the'description of my invention as set forth hereinafter, numerous advantages result by use in dependent combination of the aforesaid salts and metal sulfonates, particularly, in that such a combination possesses rust-inhibiting characteristics substantially more effective than would generally be expected from a summation of the effectiveness of the individual components thereof. Thus from a particularly practical aspect, practice of this invention enables use of a considerably smaller amount of the salt than would normally be required by use of the salts per se in order to obtain the same or improved degree of rust-preventive characteristics. Since such salts are generally more expensive than the metal sulfonates and, as is shown more fully hereinafter, use in combination of such salts with the less expensive sulfonates results in rustinhibiting characteristics substantially greater than would be expected from summation of the individual effectiveness thereof, the present invention provides a very economical means for protecting metals against rusting.

Hence, broadly speaking, the present invention relates to a composition comprising a suitable vehicle that is substantially non-corrosive to metals having dissolved therein a two-component rust-inhibiting agent in an amount sufficient 'to impart substantial rust-preventive characteristics to said vehicle. The vehicles and components of the. rust-inhibiting agent embodied for use in practicing the invention are described more fully hereinafter with illustrative examples thereof.

With reference to the vehicles, the invention broadly embodies use of organic substances that possess at least the following characteristics: (a) are not substantially, if at all, corrosive to metals, particularly ferrous metals and (b) are solvents for rust-inhibiting amounts of the metal sulfonates and salts used in the rust-inhibiting agent of this invention. The vehicles which may be employed and which possess the aforesaid essential characteristics may be non-dryin type substances, or they may be substances of the volatile type. In preferred embodiment, hydrocarbons of the volatile and non-volatile types are employed in practicing the invention. Illustrative thereof are the non-volatile type of substances derived from mineral oils and fractions thereof, as for example, hydrocarbon lubricating oils, greases, petrolatum, and the like, and volatile substances of the aliphatic and aromatic types such, for example, as naphtha, benzene, and similar substances.

As aforesaid, the compositions embodied herein comprise suitable vehicles as aforedescribed having dissolved therein a two-component rustinhibiting additive. One of said components is a suitable metal sulfonate which desirably consists of an alkali or alkaline earth metal sulfonate such, for example, as those derived from petroleum mahogany acids. A particularly effective compound of the latter type is sodium sulfonate, a composition of which is known to the art as Petronate, containing about 60 to of sodium sulfonate dissolved in a mineral oil. The other essential component of the rustinhibiting agent is a salt formed by an acid ester of a phosphorus acid with an esterified alkylolamine, such as may be formed by subjecting a suitable acid phosphate to addition reaction with a suitable esterified alkylolamine.

The acid esters that may be employed for preparation of the esterified alkylolamine salts may broadly be defined as esters of phosphorus acids that contain at least one acidic hydrogen, e. 3., partially esterified phosphorus acids. For purposes of illustration, examples thereof include partially esterified compounds such as the mono and di-esters of phosphoric acid, and mixtures of solution, the addition product thereof.

such esters, and, in further illustration, esters such as the aliphatic, alicyclic, and aryl acid esters of orthophosphoric acid. Still more specifically, the invention preferably contemplates use of acid esters of phosphorus acids that contain, as the residue of an esterifying alcohol, a hydrocarbon group containing a relatively large number of carbon atoms, as for example, from about 4 to about 30 carbon atoms. Illustrative of esters falling within the more preferred embodiments of this invention are the aliphatic acid esters, such as may be illustrated by the octyl acid phosphates including the 2-ethylhexyl acid phosphates, lauryl acid phosphates, mixtures of such aliphatic acid esters, alicyclic acid esters such as the cyclohexyl and di-cyclohexyl acid phosphates, aryl acid phosphates, and alkyl substituted aryl acid phosphates, such for example as cardanyl acid phosphates, and the like.

With reference to the esterified alkylolamines embodied herein for addition reaction with the aforesaid acid esters, the invention contemplates use of primary, secondary and tertiary amines that contain at least one alkylol group esterifled with a suitable organic acid. For purposes of illustration, such amines include esterified primary alkylolamines, e. g., esterified monoethanol amine, monoisopropanol amine, and the like; secondary amines that contain at least one alkylol group, e. g., diethanol amine, and phenylethanol amine, having one or both of the alkylol groups esterified, and tertiary amines that contain one to three alkylol groups and have at least one of the alkylol groups esterified with a suitable organic acid. Illustrations of such tertiary amines include diethyl ethanol amine, triethanol amine, triisopropanol amine, dimethyl ethanol amine, ethylphenylethanol amine, dibutyl ethanol amine, and the like. In preferred embodiment, the invention contemplates use of amines that contain an alkylol group esterified with an aliphatic acid containing a relatively long hydrocarbon chain, as for example, esterified with organic acids of the fatty acid series and, more particularly, such acids that contain a hydrocarbon chain of about 4 to about 30 carbon atoms. More specific illustrations of such amines include beta (N-dimethyl) aminoethyloleate, beta (N- diethyl) amlnoethylstearate, beta (N-diethyl) aminoethyloleate, beta (N-ethanol) aminodiethyfoleate, beta aminoethyloleate, and the like. Such esterified alkylolamines, and methods for preparation thereof are known to those skilled in the art, and hence, it is not deemed necessary to include herein a detailed description for preparation thereof.

In practicing the present invention, various methods may be employed for preparing the novel rust-inhibiting compositions. One method is to prepare the salt formed by the acid phosphate with the esterified alkylolamine and dissolve the desired amount of the salt in the vehicle, the metal sulfonate being dissolved in the vehicle either prior to, simultaneous with, or subsequent to addition of the salt to the vehicle. Another method is to separately dissolve the acid ester and the esterified alkylolamine in the vehicle whereupon the two substances react therein at room temperature to form, in When the salt is thus formed, the metal sulfonate is dissolved in the vehicle. When the latter method is employed, it is preferred that the salt be formed in the vehicle prior to addition of the sulfonate in order to avoid the .tendency of the acid ester to react with the sulfonate which would result in removal of acid ester from the reaction mixture, thus preventing the desired combination of the acid ester with the esterified' alkylolamine. Although, in preparing the salt in the vehicle in accordance with the latter method, a substantial excess of the acid ester over a mole to mole ratio with the amine should be avoided, a slight excess of the acid ester may be employed without generally encountering deleterious reaction with the sulfonate subsequently dissolved in the vehicle. Hence, in instances wherein it may be desired to employ an excess of the acid ester, wherein the final composition will contain the free acid ester in solution, it is preferable that the ratio of acid ester to amine be maintained within the ratio of about 1 to about 1.5 moles of acid ester to one mole of the amine.

The salts formed by an acid phosphate with an esterified alkylolamine, when dissolved in a suitable vehicle, impart rust-inhibiting characteristics thereto as is disclosed in my copending application, Serial No. 775,755. Moreover, and as is known to those skilled in the art, metal sulfonates such as the sodium salts of mahogany acids exhibit a certain degree of rust-inhibiting characteristics when applied to metals. However, as is evidenced by the data set forth hereinafter, use of a metal sulfonate in combination with the salt, as aforedescribed, provides a degree of rust-inhibiting characteristics that is much more efiective than would be expected from a summation of the individual effectiveness of the salt or the metal sulfonate when either of these materials is used individually in a concentration equivalent to use of a combination of the salt with the sulfonate. The use of the metal sulfonate in combination with the salt not only permits use of considerably less amounts of the salt to obtain a high degree of rust-inhibition, but use of such a combination results in considerable economics as the metal sulfonates are relatively inexpensive as compared to the salts. A further and important feature lies in the fact that these compositions form stable solutions. Obtainment of solution stability, as we'l as rust-inhibiting effectiveness, in compositions containing complex additives, constitutes a major problem in the art. The present discovery of components having compatible solubility characteristics, while at the same time exhibiting highly effective rust-inhibiting characteristics and other desired properties,

is a major advance in the art.

Although the exact reasons underlying the obtainment of highly effective rust inhibiting characteristics by practicing this invention are not fully known, it is believed that such results are apparently caused by co-action or interdependency between the additive components. The additive materials are highly polar in character which may account at least in part for the powerful rust-preventive properties. Presumably,

. this polar structure is also responsible for an atmospheres such as salt spray or mist. The com- 7 positions of this invention not only adhere tenaciously to metal surfaces but provide protection thereof under a wide variety of adverse conditions. Still another desired characteristic of the compositions disclosed herein is that they are not readily removable by water from metal surfaces to which the compositions have been applied.

In order to further describe the invention, without intent of limitation thereto, the following tabulation sets forth an illustrative embodiment of the highly effective rust-preventive characteristic provided by use of compositions such as embodied herein. For purposes of comparison, the tabulation also contains examples of the rust-inhibiting effectivenes 'of the salts or the sulfonate when used individually. In the examples, the rust-preventive characteristics of the compositions described were determined by subjecting the compositions to the severe rustinducing conditions of the humidity corrosion test described in Army-Navy Aeronautical Specification Compound: Corrosion-Preventive; Aircraft Engine AN-V'V-C576b. In accordance with the test, two freshly sandblasted steel panels are coated on all surfaces with the test oil, drained for at least four hours in an atmosphere of 50-55% relative humidity at 25 C., and then subjected to a circulating atmosphere of 95-100% relative humidity at a temperature of 120 F. for 150 hours in a special humidity cabinet. At the end of the test period, the panels are removed from the humidity cabinet, cleaned with naphtha, and examined. The presence of any corrosion in the panels, except within 4;" from any edge, evidences failure of the test composition. The compositions set forth in the following tabulation were prepared by use of a heavy parailine oil of SAE 40 grade and the salt employed was prepared by addition reaction between B (N-diethyl) aminoethyloleate and Ortholeum 162, a composition comprising a mixture of monoand di-lauryl acid phosphates.

6 hours was obtained which is considerably in excess of the protection afforded by a 4% concentration of the salt or sulfonate used individually. Test No. 4 still further illustrates that by use of the aforesaid components in combination in a. total concentration of 4%, but in a 1:1 ratio, a test life of more than 1320 hours was obtained. Test No. 5 illustrates that by use of a total concentration of 4% of the combination additive, wherein the amount of the salt was as low as 0.5%, protection for 160 hours resulted which, when compared with the results expected'from the average additivity of Test No. 1 and Test No. 2, using a ratio of one part of salt to seven of the sulfonate, is considerably in excess of expected .valnes based on additivity. Tests Nos. 6 and 7 still further show that by use of a total of 2% of the combination additive, wherein the salt to sulfonate was employed in ratios of 1:3 and 3:1, respectively, an unexpected degree of rust protection of 528 and 420 hours was obtained which, again, illustrates the exceedingly high degree of rust protection provided by practicing the present invention, such values being highly unexpected in view of the protection obtained by individual use of the salt or sulfonate in equivalent concentrations.

As aforesaid, and as illustrated by the data set forth hereinbefore, the compositions embodied herein comprise a suitable solvent vehicle having dissolved therein a rust-inhibiting amount by weight of the two component agent aforedescribed. For most usages in coating of metals for protection thereof against rusting, the total concentration of the rust-inhibiting agent need not exceed about 10% based on the weight of the vehicle. Although amounts in excess of 10%, as for example, up to about 20%, or in some cases, up to of the rust-inhibiting agent may be employed, in most instances such larger amounts are unnecessary as smaller proportions have been found to be highly satisfactory. Thus, in practicing this invention, the total concentration of additive usually employed varies from about 0.5%

Compositions (by wt.)

Ratio of Salt Humidity Cabinet Test Test No. s d Suliong; weccilfilfaabgion AN- 0 mm weig 011 Salt Sulfonate y 1 9896 2-4 168-260 hours. 2 98-96 2-4- 65-120 hours. 3 96 1 3 1:3 more than 360 hours. 4 96 2 2 1:1 more than 1,320 hours. 5 96 0.5 3. 5 1:7 160 hours. 6 98 0. 5 1. 5 1:3 528 hours. 7 98 1. 5 0.5 3:1 420 hours.

Referring to the data set forth in the foregoing tabulation, Tests Nos. 1 and 2 show the results obtained by use of the salt or the metal sulfonate alone, in 2 to 4% concentrations. In those tests, the salt, as shown, provided protection for 168 to 260 hours whereas the metal sulfonate was far less effective as evidenced by providing protection for only 65 to 120 hours. Hence, based on additivity, it would clearly be expected that by use of a combination of the salt with the sulfonate, in concentrations of 2 to 4%, the maximum life in hours would not be as effective as the salt itself. However, as is evidenced by the foregoing data, use of the aforesaid components in combination provides a completely unexpected degree of rust-prevention. For example, Test No. 3 shows that by use of the salt and sulfonate in combination, in a total concentration of 4%. and in a ratio of 1:3, a test life of more than 360 to about 20%, and more preferably. from about 2.0% to about 10.0%. Moreover, and as is evidenced by the data in the foregoing tabulation, highly satisfactory performance is obtained by using the salt in a concentration of at least about 0.5% based on the weight of the vehicle and the suifonate in an amount of about one-third to about seven times the weight of the salt, such a ratio and concentration of salt being set forth in Test No. 5, using a one to seven ratio by weight of salt to sulfonate, and Test No. 9, using a three to one ratio of salt to sulfonate. Hence, from a practical and preferred aspect, the present invention embodies as rust-inhibiting compositions for application to metals, 9. suitable vehicle as aforedescribed having dissolved therein at least about 0.5% by weight of a salt (as aforedescribed) and a suitable metal sulfonate II in an amount varying from about one-third to protection results from use thereof.

about seven times the weight of the 'salt. Al'- ,-the salt, may be employed, use of the higher con- 'centrations of the sulfonate are preferred as the degree of rust-protection afforded thereby is materially improved over the performance of the salt itself, and in many instances, more consistent results are obtained. n the other hand, use

of the sulfonate in excess of a ratio of one part of salt to about seven parts of sulfonate may be employed but, use of the sulfonate in excess thereof, though not generally deleterious, is not usually employed as such excessive use of sulfonates does not appear to impart further improvement other than what may result from the rust-preventive characteristics of the-sulfonate itself. Hence, use of the sulfonate in excess of a ratio of one part of salt to about seven parts of sulfonate is generally not employed for the aforesaid reason as well as for purposes of economy.

In the aforesaid description of my invention,

particular emphasis has been placed on compositions embodied herein that contain a minor amount of the rust-inhibiting agent based on the weight of vehicle as, for most usages,highly effective metal protection is generally provided by use of such compositions. within the scope of the invention to include compositions comprising a suitable solvent vehicle as aforedefined having the rust-inhibiting agent dissolved therein and in which the rust-inhibiting agent is the major constituent by weight.

Although compositions containing such a high concentration of rust-inhibiting agent may be employed for actual application to metals to protect against rusting, for most purposes, much lower concentrations are used as highlyadequate However, the highly concentrated solutions of the rust-inhibiting ingredient are particularly useful as concentrates for use in blending with a suitable vehicle to provide rust-inhibiting compositions in which the rust-inhibiting agent comprises a minor but rust-inhibiting amount. particularly for use as concentrates for such blending purposes, the present invention also embodies compositions that comprise a suitable noncorrosive solvent vehicle, having dissolved therein a high concentration, e. g., over 50% by weight,

However, it is 1 Thus, and

-third to three parts by ations are to be considered to be within the provision of the specification and scope of the appended claims.

I claim:

1. As a new composition, a hydrocarbon vehicle having dissolved therein about0.5 to about 2.0% by weight of a rust-inhibiting salt formed by mole to mole'addition reaction of acid lauryl phosphate with B(N-diethyl) aminoethyloleate and about 0.5 to about 3.0% by weight of a sodium salt of petroleum mahogany acids, said composition being f-urther characterized by containing said sodium salt in an amount of about oneweight of the rust-inhibiting salt.

2; As a new composition, a hydrocarbon vehicle having dissolved therein a small but rust-inhibiting amount of (a) a rust-inhibiting salt formed by mole to mole addition reaction of acid lauryl phosphate and B(N-diethyl) aminoethyloleate and (b) a sodium salt of petroleum mahogany acids in an amount of about one-third to about three times the weight of said rust-inhibiting salt and suificient to impart to said composition rust-inhibiting characteristics in excess of the individual effectiveness of said sodium salt and rust-inhibiting salt.

3. As a new composition, a hydrocarbon vehicle having dissolved therein a small but rust-inhibiting amount of (a) a rust-inhibiting salt formed by mole to mole addition reaction of a lauryl acid phosphate with an amine from the group consisting of B(N-diethyl) aminoethyl stearate and B(N-diethyl) aminoethyloleate and (b) 'a-sodium salt of petroleum mahogany acids in an amount of about one-third to about three times the weight of said rust-inhibiting salt and suihcient to impart 'to said composition rust-inhibiting characteristics in excess of the sum of the individual rust-inhibiting effectiveness of said sodium salt and rust-inhibiting salt.

4. A composition, as defined in claim 3, wherein the vehicle is a mineral oil.

'acid phosphate containing an alkyl group of eight to twelve carbon atoms and an amine from the group consisting of B(N-diethyl) aminoethyloleate and B(N-diethyl) aminoethylstearate, and

of the rust-inhibiting agent. Suitable illustrations thereof comprise a hydrocarbon vehicle' having dissolved therein amounts in excess of by weight of the rust-inhibiting agent, the

maximum concentration being dependent upon the particular vehicle employed and the solubility thereof for the rust-inhibiting agent. In such compositions, the ratio of salt to sulfonate is preferably maintained within the range of one part of salt to about one-fifth to about seven parts of sulfonate. or still more preferably, to

about one-third to about seven parts' of sulfonate, whereby, upon use of such concentrated compositions for blending purposes, the resulting blend will contain the salt to sulfonate in such weight ratios which, for reasons aforedescribed, provide the effective rust-preventive characteristics defined herein. Although the present invention has been described in conjunction with certain'preferred embodiments thereof, those skilled in the art will -(b) a sodium salt of petroleum mahogany acids in an amount of about one-third to about three times the weight of said rust-inhibiting salt and suflicient to impart to said composition rustinhibiting characteristics in excess of the individ-ual effectiveness of said sodium salt and said rust-inhibiting salt.

JOHN BISHOP.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

5. AS A NEW COMPOSITION, A HYDROCARBON VEHICLE HAVING DISSOLVED THEREIN A SMALL BUT RUST-INHIBITING AMOUNT OF (A) A RUST-HIBITING SALT FORMED BY MOLE TO MOLE ADDITION REACTION OF AN ACID PHOSPHATE CONTAINING AN ALKYL GROUP OF EIGHT TO TWELVE CARBON ATOMS AND AN AMINE FROM THE GROUP CONSISTING OF B(N-DIETHYL) AMINOETHYLOLEATE AND B(N-DIETHYL) AMINOETHYLSTEARATE, AND (B) A SODIUM SALT OF PETROLEUM MAHOGANY ACIDS IN AN AMOUNT OF ABOUT ONE-THIRD TO ABOUT THREE TIMES THE WEIGHT OF SAID RUST-INHIBITING SALT AND SUFFICIENT TO IMPART TO SAID COMPOSITION RUSTINHIBITING CHARACTERISTICS IN EXCESS OF THE INDIVIDUAL EFFECTIVENESS OF SAID SODIUM SALT AND SAID RUST-INHIBITING SALT. 